Higher AnimalsHigher AnimalsChapter 13Chapter 13

MollusksMollusks Mollusks are soft-bodied, invertebrates, that Mollusks are soft-bodied, invertebrates, that

have bilateral symmetry, and usually one or two have bilateral symmetry, and usually one or two shells.shells.

Mostly they live in water but some live on land. Mostly they live in water but some live on land. Snails, clams, and squid are examples.Snails, clams, and squid are examples.

All mollusks have a mantle, or a thin tissue layer, All mollusks have a mantle, or a thin tissue layer, that covers all of its organs.that covers all of its organs.

The mantle contains gills, which exchange CO2 The mantle contains gills, which exchange CO2 for the oxygen in the water.for the oxygen in the water.

The mantle also secretes the shell of the The mantle also secretes the shell of the mollusk, which protects the animal. As the mollusk, which protects the animal. As the mollusk grows more shell material is produced.mollusk grows more shell material is produced.

Mollusks have open circulatory systems which Mollusks have open circulatory systems which means that blood is pumped into open spaces means that blood is pumped into open spaces that surround organs.that surround organs.

Mollusk classificationMollusk classification

First we classify them by seeing if they First we classify them by seeing if they have shells. The ones that do have shells have shells. The ones that do have shells are then classified by the type of foot that are then classified by the type of foot that they have.they have.

Gastropods- Largest group, and include Gastropods- Largest group, and include snails, and conches. These mollusks have snails, and conches. These mollusks have a single shell and a radula, which is a a single shell and a radula, which is a tongue like organ used to obtain food.tongue like organ used to obtain food.

They move contracting their muscular foot, They move contracting their muscular foot, that secretes mucus to allow them to slide that secretes mucus to allow them to slide in a particular direction.in a particular direction.

BivalvesBivalves

These mollusks have a hinged two part These mollusks have a hinged two part shell, and are clams, muscles, and shell, and are clams, muscles, and oysters. They open and close these shells oysters. They open and close these shells by using muscles near the hinge.by using muscles near the hinge.

These shells can be used for both These shells can be used for both protection from predators and can also be protection from predators and can also be used to help in movement of the mollusk used to help in movement of the mollusk through the water.through the water.

H.W.- pg 368 ques. 1-4H.W.- pg 368 ques. 1-4

Cephalopod Cephalopod These are the most complex of the mollusks. These are the most complex of the mollusks.

Squids, octopi belong to this group.Squids, octopi belong to this group. These are predators and feed on fish and other These are predators and feed on fish and other

marine organisms. They have well developed marine organisms. They have well developed nervous systems with a large eye and closed nervous systems with a large eye and closed circulatory systems. Blood does not pool up and circulatory systems. Blood does not pool up and surround the organs here, it is pumped into the surround the organs here, it is pumped into the organ by tiny vessels.organ by tiny vessels.

Cephalopods are great swimmers and can Cephalopods are great swimmers and can propel themselves by filling up a hollow body propel themselves by filling up a hollow body cavity and squeezing it out to shoot them in a cavity and squeezing it out to shoot them in a certain direction.certain direction.

Segmented Worms or AnnelidsSegmented Worms or Annelids These worms have tube shaped bodies These worms have tube shaped bodies

and are divided into many segments.and are divided into many segments. Each segment contains setae, or a brisstle Each segment contains setae, or a brisstle

like structure that aids them in moving like structure that aids them in moving around in the ground.around in the ground.

They have bilateral symmetry, a body They have bilateral symmetry, a body cavity that holds organs, and 2 body cavity that holds organs, and 2 body openings, a mouth and an anus.openings, a mouth and an anus.

Ex: earthworms, leachesEx: earthworms, leaches

Body structureBody structure They have a front end and a rear end, and over They have a front end and a rear end, and over

100 body segments. Each segment has 4 pairs 100 body segments. Each segment has 4 pairs of setae.of setae.

They have a set of muscles that runs the length They have a set of muscles that runs the length of the body and a set that circles the body.of the body and a set that circles the body.

When they move soil enters its mouth and When they move soil enters its mouth and moves to the worms crop, which is like a moves to the worms crop, which is like a stomach that is used for storage.stomach that is used for storage.

From the crop the food will move to the gizzard From the crop the food will move to the gizzard where the food is ground up. From here the where the food is ground up. From here the food is pushed through the intestine where food is pushed through the intestine where nutrients are absorbed, and eventually passes nutrients are absorbed, and eventually passes through the anus.through the anus.

Circulation and NervesCirculation and Nerves Annelids have a closed circulatory system with Annelids have a closed circulatory system with

two blood vessels along the top of the body and two blood vessels along the top of the body and one below the body.one below the body.

They join at the front end of the worm at a heart They join at the front end of the worm at a heart like structure called aortic arches.like structure called aortic arches.

They get oxygen by absorbing it from the air into They get oxygen by absorbing it from the air into their skin.their skin.

They have a small brain that has a nerve chord They have a small brain that has a nerve chord that connects the brain to nerves in each that connects the brain to nerves in each segment of the worm.segment of the worm.

They are hermaphrodites but reproduce They are hermaphrodites but reproduce sexually.sexually.

H.W. pg 373 ques. 1-4H.W. pg 373 ques. 1-4

ArthropodsArthropods This is the largest group of animal, and has over This is the largest group of animal, and has over

a million species. They have jointed a million species. They have jointed appendages. appendages.

These include legs, antennae, claws, and These include legs, antennae, claws, and pinchers.pinchers.

They have bilateral symmetry, segmented They have bilateral symmetry, segmented bodies, an exoskeleton, and digestive and bodies, an exoskeleton, and digestive and nervous systems.nervous systems.

Their exoskeleton cannot grow with them so Their exoskeleton cannot grow with them so they go through a shedding process called they go through a shedding process called molting. When this occurs the arthropod is very molting. When this occurs the arthropod is very unprotected.unprotected.

InsectsInsects Insects are part of the arthropod group.Insects are part of the arthropod group. Their bodies are composed of three regions, a Their bodies are composed of three regions, a

head, a abdomen, and a thorax.head, a abdomen, and a thorax. The head- has a pair of antenna, eyes and a The head- has a pair of antenna, eyes and a

mouth.mouth. The antennae are used for touch and smell, The antennae are used for touch and smell,

and the eyes can be simple or compound, and the eyes can be simple or compound, meaning they have many lenses.meaning they have many lenses.

Thorax- These segment contains three pairs of Thorax- These segment contains three pairs of legs, and sometimes, 1 or 2 pairs of wings. legs, and sometimes, 1 or 2 pairs of wings.

Insects are the only invertebrate that can fly.Insects are the only invertebrate that can fly.

InsectsInsects Abdomen- This sections contains the Abdomen- This sections contains the

reproductive structures, and an open reproductive structures, and an open circulatory system.circulatory system.

The open circulatory system carries The open circulatory system carries digested food to cells and removes waste.digested food to cells and removes waste.

Insects do not have blood to carry oxygen, Insects do not have blood to carry oxygen, but they have spiracles, or openings in the but they have spiracles, or openings in the thorax and abdomen which oxygen passes thorax and abdomen which oxygen passes through and waste gases leave.through and waste gases leave.

Insects Insects

They obtain food by eating plants, the They obtain food by eating plants, the blood of animals, nectar, decaying blood of animals, nectar, decaying materials, wood, and clothing materials.materials, wood, and clothing materials.

Depending on the type of diet that an Depending on the type of diet that an insect has, they will have different mouth insect has, they will have different mouth pieces. pieces.

Grasshoppers have large mandibles Grasshoppers have large mandibles (jaws) that allow for chewing grass. And (jaws) that allow for chewing grass. And bees will have siphons that they use to lap bees will have siphons that they use to lap up honey.up honey.

ArachnidsArachnids

Spiders, scorpions, mites, fleas, and ticks Spiders, scorpions, mites, fleas, and ticks are arachnids.are arachnids.

They have 2 body regions, a They have 2 body regions, a cephalothorax, and an abdomen.cephalothorax, and an abdomen.

They have 4 pairs of legs and no They have 4 pairs of legs and no antennae.antennae.

They kill their prey using fangs or stingers They kill their prey using fangs or stingers that are connected to poison glands.that are connected to poison glands.

Centipedes & MillipedesCentipedes & Millipedes They have long bodies with many They have long bodies with many

segments, exoskeletons, jointed legs, segments, exoskeletons, jointed legs, antennae, and simple eyes.antennae, and simple eyes.

They make nests for their eggs and stay They make nests for their eggs and stay with them until they hatch.with them until they hatch.

Centipedes hunt their hunt their prey Centipedes hunt their hunt their prey which included snails ,slugs, and worms.which included snails ,slugs, and worms.

Millipedes feed on plants and decaying Millipedes feed on plants and decaying material found under damp plant material.material found under damp plant material.

Crustacean Crustacean Crabs, lobster, shrimp are examples of these.Crabs, lobster, shrimp are examples of these. These live in water and have 1 or 2 pairs of These live in water and have 1 or 2 pairs of

antennae and mandibles that are used to crush antennae and mandibles that are used to crush food.food.

Mostly they live in water, but some live on land, Mostly they live in water, but some live on land, like pill bugs.like pill bugs.

They have 5 pairs of legs, one of which is a set They have 5 pairs of legs, one of which is a set of claws. All of these legs have the ability to of claws. All of these legs have the ability to regenerate.regenerate.

H.W. pg 382 ques. 1-4H.W. pg 382 ques. 1-4

EchinodermsEchinoderms

Echinoderms have a hard endoskeleton Echinoderms have a hard endoskeleton that is covered by a thin, bumpy or spiney that is covered by a thin, bumpy or spiney epidermis. Ex: Sea starepidermis. Ex: Sea star

They have a mouth stomach and They have a mouth stomach and intestines and also radial symmetry, which intestines and also radial symmetry, which allows them to sense food and prey all allows them to sense food and prey all around them.around them.

They have no brain or head, but do have a They have no brain or head, but do have a nerve ring that surrounds the mouth.nerve ring that surrounds the mouth.

EchinodermsEchinoderms

They have a water-vascular system, a They have a water-vascular system, a network of water-filled canals with network of water-filled canals with thousands of tube feet connected to it.thousands of tube feet connected to it.

Tube feet are small suction cupped feet Tube feet are small suction cupped feet that allows the animal to move.that allows the animal to move.

A sea star is an echinoderm that has at A sea star is an echinoderm that has at least 5 arms arranged around a central least 5 arms arranged around a central point. They have thousands of tube feet point. They have thousands of tube feet on them.on them.

EchinodermsEchinoderms

Sea Urchins & sea dollars and disk or Sea Urchins & sea dollars and disk or globe shaped animals that are covered in globe shaped animals that are covered in spines.spines.

They do not have arms but they do have They do not have arms but they do have spines for protection.spines for protection.

H.W. 394 ques. 1-15H.W. 394 ques. 1-15